The present invention relates generally to cooling of gas turbine engine components and more specifically to cooling of adjoining mate faces in cooled gas turbine engine components, such as shrouds and platforms.
Gas turbine engines operate by passing a volume of high energy gases through a plurality of stages of vanes and blades, each having an airfoil, in order to drive turbines to produce rotational shaft power. The shaft power is used to drive a compressor to provide compressed air to a combustion process to generate the high energy gases. Additionally, the shaft power is used to drive a generator for producing electricity, or to drive a fan for producing high momentum gases for producing thrust. In order to produce gases having sufficient energy to drive the compressor, generator and fan, it is necessary to combust the fuel at elevated temperatures and to compress the air to elevated pressures, which also increases its temperature. Thus, the vanes and blades are subjected to extremely high temperatures, often times exceeding the melting point of the alloys comprising the airfoils. High pressure turbine blades are subject to particularly high temperatures.
In order to maintain gas turbine engine turbine blades at temperatures below their melting point, it is necessary to, among other things, cool the blades with a supply of relatively cooler air, typically bled from the compressor. The cooling air is directed into the blade to provide convective cooling internally and film cooling externally. For example, cooling air is passed into interior cooling channels of the airfoil to remove heat from the alloy, and subsequently discharged through cooling holes to pass over the outer surface of the airfoil to prevent the hot gases from contacting the vane or blade directly. Various cooling air channels and hole patterns have been developed to ensure sufficient cooling of various portions of the turbine blade.
A typical turbine blade is connected at its inner diameter ends to a rotor, which is connected to a shaft that rotates within the engine as the blades interact with the gas flow. The rotor typically comprises a disk having a plurality of axial retention slots that receive mating root portions of the blades to prevent radial dislodgment. Blades typically also include integral inner diameter platforms that prevent the high temperature gases from escaping through the radial retention slots. It is desirable to further provide targeted cooling to the platforms to cool the surfaces between adjacent platforms. There is a continuing need to improve cooling of turbine blade platforms to increase the temperature to which the blade can be exposed, thereby increasing the overall efficiency of the gas turbine engine.